So for 20 years me and my 73 convertible have toughed out South LOUISIANA heat. Now with global warming I have the excuse I needed to put in A/C. I know this has been researched in the forum threads before but I am asking again because times change and I can't find the links. All help is appreciated thank you .

If you want it to look original the easiest thing to do is find a donor car. Can be any body style all the same air. Your non air car has an air vent on the drivers side that is not used with air but could stay in if it does not get in the way of the ducts for the air. It is actually easier to put air in to look original than to take air off. About all you have to alter on the body is to cut the hole in the firewall for the air and heater hoses to go through. There should be several threads on the subject. I know I posted lots of pictures for another member and also made a template for the cut out in the firewall.
You can go aftermarket if you are not worried about original but I have never done that.
I searched Craigslist and found a rust bucket vert that had Air, Power Windows, Power Steering, Power Disc Brakes, Console, Gauges, AM/FM, 351 C 2-V automatic. Got the entire car for $1,000 down south of Atlanta. So just go looking for maybe a rusty coupe, should be cheaper, and get the whole thing. That way you get all the brackets for engine / air and you can see how it is installed. I think all three years are pretty much the same.
It will be far easier to install with the entire dash pulled. You will need to change wire harness also and a 73 Vert is difficult to find not hacked. Midlife can add what you need to your harness probably easiest unless you get a donor car with good harness. Rebuild the heater box which is also in past threads. It is not a task anyone that does not like complicated assembly and attention to details should start.
Take what you need off the car part it out and sell for scrap when done.
Good luck would be a great winter project when you are not cruising.

When a man is in the woods and talks and no women are there is he still wrong??David